This suspected plane part found on the southern coast of South Africa may be from one of Malaysia Airlines Flight 370's Rolls-Royce engines (AP)The crew of survey ship HMS Echo joined the search in the southern Indian Ocean for the missing Malaysia Airlines plane (MoD/PA)

Two pieces of debris discovered along the coast of Mozambique are "highly likely" to have come from missing Malaysia Airlines Flight 370, Australian authorities have said.

An analysis of the parts by an international investigation team showed both pieces were consistent with panels from a Malaysia Airlines Boeing 777, transport minister Darren Chester said.

"The analysis has concluded the debris is almost certainly from MH370," he said.

The discovery of the two pieces provide another piece of the puzzle into the plane's fate and bolster authorities' assertion that the plane went down somewhere in the Indian Ocean.

But whether they can provide any clues into exactly what happened to the aircraft and why is uncertain.

Flight 370 disappeared on March 8 2014 with 239 aboard and is believed to have crashed somewhere in a remote stretch of the southern Indian Ocean about 3,700 miles east of Mozambique.

Authorities had predicted that any debris from the plane not on the ocean floor would eventually be carried by currents to the east coast of Africa.

Until now, the only other confirmed piece of debris from the Boeing 777 was a wing part that washed ashore on the French Indian Ocean island of Reunion last year.

Given the vast distances involved, the variability of winds and the time that has elapsed, it is impossible for experts to retrace the parts' path back to where they first entered the water. And chances the debris itself could offer any fresh clues into precisely where the plane crashed are slim.

"Close examination of the debris might possibly give some additional information relative to the search, but it's unlikely," said Dan O'Malley, spokesman for the Australian Transport Safety Bureau, which is leading the hunt for the plane off Australia's west coast.

In a bid to glean whatever information they could, investigators from Australia, Malaysia, and Boeing spent several days scrutinising both pieces. The parts were rinsed, submerged and agitated in water to capture any loose marine life. The water was then sieved and any potential biological material that was captured will be examined to see if it can be identified.

Experts will also probably examine the debris to see if it can offer any hints about what happened on board, such as structural deformities that could show the angle at which the plane entered the ocean or markings that could indicate a mid-air explosion.

Still, that would take some luck as the wing part found on Reunion Island has not yet yielded any significant revelations into the plane's fate.

What investigators really need to find is the main underwater wreckage, which would hold the plane's coveted flight data recorders, or black boxes. The data recorder should reveal details related to the plane's controls, including whether aircraft systems that might have helped track the plane were deliberately turned off, as some investigators believe.

But prospects for finding the debris field are running thin. Crews have already covered more than 70% of the search zone, and expect to complete their sweep of the area by the end of June. No trace of the underwater wreckage has been found.

One of the parts in Mozambique was discovered by American lawyer and part-time adventurer Blaine Gibson, of Seattle. Mr Gibson, who said he had been searching for Flight 370 over the last year, found the piece on a sandbank.

Mr Gibson said he hoped the part could provide investigators some leads into where and how the plane crashed, but felt little joy over the news that his discovery almost certainly came from Flight 370.

"I do not use the word 'happy'," he said on Thursday from Burma, where he was visiting friends. "Because 'happy' - that is how I would feel if I arrived on that sandbank and found all the passengers and crew alive, sipping on coconuts and grilling seafood and saying, 'What took you so long?'

"That would make me happy. However we're after the truth, whatever it is."

Soon after his find was publicised, a South African teenager realised a piece of grey debris he found on a beach during a family holiday in Mozambique might also be from the plane.

Liam Lotter, 18, came upon it while strolling on a beach in southern Mozambique in December and thought it might be from an aircraft.

His parents dismissed it as rubbish that may have come from a boat, but he insisted on bringing it back to South Africa to research the fragment.

Once back at home, the piece ended up in storage alongside the family's fishing gear and was nearly forgotten.

It was only when Mr Lotter read about Mr Gibson's find about 186 miles from where he had made his discovery that the family alerted authorities.

Earlier this week an archaeologist walking along South Africa's southern coast found a piece of debris with part of an aircraft engine manufacturer's logo.

Malaysian transport minister Liow Tiong Lai said there was a possibility it came from an inlet cowling of an aircraft engine and authorities will examine it to see if it, too, came from Flight 370.